Method for the continuous decatizing of fabrics

ABSTRACT

A method of continuous decatizing includes the steps of passing a fabric to be decatized around a steaming cylinder and around a suction cylinder. A backing cloth which applies pressure to the fabric can be tensioned by different amounts at each cylinder.

United States Patent Riedel 1 May 27, 1975 1 METHOD FOR THE CONTINUOUS {56] References Cited DECATIZING OF FABRICS UNITED STATES PATENTS [75] Inventor; Dieter Riedel, Hausberge/Pona, 2,054.391 9/1936 Schmidt 34/116 X Germany 2.885.875 5/1959 Sperotto 68/5 D ux [73] Assignee: Drabert Sohne, Minden, Westphalia, FOREIGN PATENTS OR APPLICATIONS Germany 749,084 5/1956 United Kingdom 8/l49.3

[22] Filed: 1973 Primary Examiner-Harvey C. Hornsby [2]] App]. No.: 342,549 Assistant Examiner-Philip R. Coe

Attorney, Agent, or FirmMason, Mason & Albright [30] Foreign Application Prlorlty Data ABSTRACT 1972 Germany 2213429 A method of continuous decatizing includes the steps of passing a fabric to be decatized around a steaming g6 cylinder and around a suction cylinder. A backing Field D 5 E 8 cloth which applies pressure to the fabric can be tensioned by different amounts at each cylinder.

5 Claims, 5 Drawing Figures PATENTEU HAY 2 7 IQYS SHLU 2 UF 5:

1 METHOD FOR THE CONTINUOUS DECATIZING OF FABRICS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for the continuous decatizing of fabrics.

2. Description of the Prior Art A steaming apparatus is known in which a fabric web together with a backing cloth passes over a plurality of steaming rollers and deflecting rollers arranged inside a vacuum chamber. A disadvantage of this prior proposal is the relatively small area of the fabric web on which the steam acts.

A further disadvantage of this previously proposed apparatus is that as a result of the numerous deflection points for the fabric and the backing cloth a relatively low surface pressure is exerted during the steaming period and the cooling period, on the fabric that is to be decatized.

A continuously operating decatizing machine with a felt backing cloth travelling round a cylinder has also been proposed. In this apparatus part of the cylinder is used for steaming and another part for applying suction to the fabric. The surface pressure caused by the tensile force in the backing cloth is the same in both the steaming period and in the suction period.

Continuously operating decatizing machines are thus known which move the fabric to be treated together with a backing cloth over one or more perforated drums in order to effect a steaming and suction process. In these machines usually only one drum is driven and surface pressure is exerted by the tensile force applied to the backing cloth.

For obtaining a different action as regards the decatizing effect, with such machines, it is possible to obtain only a slight difference by changing the fabric throughput speed and adjusting the surface pressure during decatizing by changing the tensile force applied to the backing cloth.

Irrespective of the tensile force under which the backing cloth may travel, in previously proposed decatizing machines the magnitude values for the surface pressure for the steam treatment remain the same as those for suction.

Intensive research regarding effective decatizing has resulted in further knowledge. If, for instance, the factors influencing the decatizing effect of previously pro posed discontinuous batch decatizing are to be considered in relation to continuous decatizing, different principles and considerations have to be borne in mind or allowed for.

If approximately the same decatizing effect as regards the feel of the fabric, the thickness of the fabric and the surface lustre of the fabric is to be obtained with the two previously proposed methods and apparatus, then in the continuous process it is necessary to operate with a substantially higher surface pressure because of the far shorter action and treatment time. But the transfer of this knowledge to the previously proposed continuously operating decatizing machines involves certain disadvantages and gives rise to numerous problems. At this point it is not necessary to discuss the question as to whether the surface pressure values necessary for effective decatizing effects can be obtained in practice at all.

The essential disadvantages of the previously proposed continuously operating decatizing machines are that a relatively high surface pressure during steaming and during suction leads to a reduction in the thickness of the fabric, and this reduction is generally not desired. Also, the shrinking process is impeded by relatively high surface pressures during steam treatment.

For these reasons, previously proposed continuously operating decatizing machines operate with substantially smaller surface pressure. However, the decatizing effects then obtained are insufficient and therefore not comparable with those of discontinuously operating decatizing machines and are basically useful only for very light woven and knitted fabrics of low quality.

For this reason, pressure rollers arranged at the periphery of the decatizing cylinder have recently been used in such machines. However these pressure rollers can produce only slight changes in the decatizing effect and in the surface pressure, because an increased sur face pressure occurs only in the region ofa very narrow location and therefore has an extremely short duration.

It is therefore an object of the present invention to provide a method by which optimum decatization can be obtained irrespective of the kind and nature of the fabric being treated.

SUMMARY OF THE INVENTION According to the present invention there is provided a method of continuously decatizing a fabric web comprising the steps of applying steam at a steam-applying station to the fabric web as the web traverses a cylindrical path and is subjected to pressure generated by tension applied to length of backing cloth, and applying suction at a suction-applying station to the fabric web as the web traverses a cylindrical path and is subjected to pressure generated by tension applied to the length of backing cloth, the pressures in lengths of the backing cloth at the steam applying station and at the suction applying station being variable independently of one another.

BRIEF DESCRIPTION OF THE DRAWINGS Certain embodiments of decatizing apparatus for carrying out the method in accordance with the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 is a vertical section through a first embodiment of decatizing apparatus for carrying out the method in accordance with the invention;

FIG. 2 is a vertical section through a second embodiment;

FIG. 3 is a section similar to that of FIG. 2 but also showing controllable transmission arrangements;

FIG. 4 is a vertical section through a third embodiment; and

FIG. 5 is a vertical section through a fourth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An endless backing cloth 1 (FIG. 1) which consists of a satin fabric or an endless belt of synthetic material or the like and serves primarily to transport the fabric 2 which is to be treated, passes over cylinders 3 and 4 under comparatively low initial tensile stress.

Each of the cylinders 3 and 4 has on its periphery a wrapping winding of the same material as the backing cloth 1, or a shrunk-on seamless tube. 5 and 6 respectively, of felt or the like. This ensures that the fabric 2 passes between the backing cloth 1 and the tube 5 or 6 and is subjected to each phase of the treatment without elongation.

In the embodiment illustrated in FIG. I the steam treatment on the cylinder 3 takes place from the inside to the outside or from the outside to the inside. On the cylinder 4, on the other hand, the fabric is subjected to suction and is cooled. The backing cloth 1 is guided over deflecting rollers and is held under initial tension by means of a tensioning hydraulic or pneumatic cylinder ll acting on a deflecting roller 110. This applies a basic tension to the whole system and thus applies a minimum surface pressure to the fabric 2 which is to be decatized.

For each of the cylinders 3 and 4 a respective feed roller 7 and 9 and a respective withdrawal roller 8 and are provided, over which the backing cloth 1 is respectively fed to and withdrawn from the corresponding cylinder 3 or 4. The backing cloth 1 is driven by the feed roller 7.

The tensile stresses in the parts of the backing cloth 1 passing round the cylinders 3 and 4 respectively can be adjusted independently of one another. Thus for instance in the embodiment according to FIG. 1 the withdrawal roller 8 has a higher speed of rotation than the feed roller 7. The effective speed of rotation of the withdrawal roller 8 is thus only a few per cent higher than the speed of the feed roller 7, so that the speed difference is available as work of deformation of the backing cloth 1 passing around the cylinder.

The high speed of rotation of the withdrawal roller 8 leads to elongation of the circulating backing cloth 1 along the section between the feed roller 7 and the withdrawal roller 8 and therefore to a directly proportional increase in the tension of the backing cloth 1 in the longitudinal direction.

A radial force or pressure also results from the longitudinal tension of the backing cloth 1, and therefore the surface pressure on the fabric 2 in the region of the cylinder 3 is also increased when the speed of rotation of the withdrawal roller 8 is higher.

The controlled speed of rotation of the withdrawal roller 8 is then directly proportionally transmitted to the feed roller 9.

The feed roller 9 thus takes over the same function for the cylinder 4 as the feed roller 7 for the cylinder 3. The withdrawal roller 10 following the cylinder 4 provides for a particular surface pressure which can be selected independently of the cylinder 3.

The tension in the backing cloth 1 can be adjusted within wide limits by way of the tensioning cylinder 11 and the deflecting roller 11a, and therefore the surface pressure exerted on the cylinder 4 can be made substantially higher than the surface pressure on the cylinder 3. This is possible only if the surface pressure resulting from the tension of the backing cloth, produced by way of the tensioning cylinder 11, acts on the cylinder 3 and the withdrawal roller 8 has a higher speed than the feed roller 7. The steaming process takes place with minimum surface pressure under these circumstances, that is to say with the low tensile force in the backing cloth 1.

The feed roller 9 receives the backing cloth 1 and the fabric 2 from the cylinder 3 at the same speed and conveys them to the cylinder 4. The maximum value of the surface pressure on the periphery of the cylinder 4 is obtained when the speed of the withdrawal roller 10 as compared with that of the feed roller 9 is a maximum.

In the embodiment of FIG. 2, three cylinders 3, 4 and 12 are used, and here too each cylinder is preceded by a respective one of feed rollers 7, 9 and I3 followed by a respective one of withdrawal rollers 8, l0 and 14.

By means of these three cylinders 3, 4 and 12 it is possible to achieve the following combinations:

a. steam treatment from the inside to the outside and from the outside to the inside on cylinder 3;

b. steam treatment from the outside to the inside on cylinder 4;

c. suction on cylinder 12; or alternatively:

d. steam treatment from the inside to the outside and from the outside to the inside on cylinder 3',

e. suction on cylinder 4;

f, suction on cylinder 12; or alternatively,

g. steam treatment from the inside to the outside and from the outside to the inside on cylinder 3, with superheated steam and under high surface pressure;

h. suction on cylinder 4 with high surface pressure;

i. steam treatment with saturated steam and under low surface pressure on cylinder 12.

It has been found, however, that particularly satisfactory results are obtained if steaming a b is first carried out on cylinder 3 with saturated steam under relatively low surface pressure and subsequently the treatment with superheated steam under far higher surface pressure is carried out on cylinder 4 and leads to stabilization of the dimensions of the fabric 2.

In the subsequent suction treatment on cylinder 12, the appropriate surface pressure for this treatment should be obtained by change of the speed of rotation of the withdrawal roller 14.

A process particularly suitable for decatizing polyester fabrics is steam treatment on the cylinder 3 with superheated steam or alternatively with saturated steam, followed by suction on both of the cylinders 4 and 12 under higher surface pressure than in the case of the steam treatment.

It also appears to be of interest that a double interaction between steam treatment and suction can be obtained if for instance first of all steaming with superheated steam is carried out from the inside to the outside or from the outside to the inside, with a relatively high surface pressure, on cylinder 3, and suction takes place with the higher surface pressure on cylinder 4 and is followed by steam treatment on cylinder 12 with saturated steam under the action of a low surface pressure.

Firstly, this treatment permits the greatest possible stabilization. However, since the high temperature of the superheated steam leads to hardening of the fabric feel and reduction in the volume of the fabric, the subsequent steam treatment with saturated steam at a relatively low surface pressure produces the required fee! and the desired volume of the fabric. The final treatment with steam should be followed by intensive cooling process in each case.

FIG. 3 of the drawings is a purely diagrammatic illustration of the drive system of the decatizing of FIG. 2. In order to simplify the presentation, an electromechanical drive is considered. However, this drive can be replaced by hydraulic or electronic and electrical drive or the like.

For regulating the surface pressure for a decatizing machine with three treatment cylinders 3, 4 and 12, four transmissions are provided in all. A transmission receives the necessary torque by way of a driving motor 16 and can be regulated within wide limits, whereby the working speed for the whole decatizing machine is finally determined. The drive is first transmitted at a suitably reduced speed to the feed roller 7 and the circulating backing cloth 1 is thereby set in motion.

The controlled speed of rotation of the transmission 15 is transmitted by way of a shaft 17 to a following transmission 18. This makes it possible to transmit a higher speed of rotation to the withdrawal roller 8 by suitable regulation of the transmission 18. This establishes an increase in the tension of the backing cloth 1 in the region of the cylinder 3 between the rollers 7 and 8, and this causes the surface pressure to rise.

The controlled speed of rotation of the withdrawal roller 8 is now transmitted directly and positively to the feed roller 9. Also, the controlled speed of rotation of the transmission 18 is transmitted by way of a shaft 19 to a further following transmission 20.

The drive speeds for the withdrawal rollers 10 and 14 can be regulated by way of transmissions 20 and 21 in the manner described above. Here too, the driven shaft 22 of the transmission 20 represents the input for the transmission 21.

When the rollers 10 and 13 have the same diameter there is a positive drive with the ratio 1:1.

In the machine of FIG. 4, a change in the surface pressure on the cylinders 3 and 4 is effected by an arrangement in which in addition to the different speed regulation for the withdrawal rollers 8 and 10 a different surface pressure in each case is exerted on the circulating backing cloths l and 1a by way of tensioning rollers 23 and 24. The whole system is thus moved not by a single backing cloth 1 but by two backing cloths 1 and la which are unequally tensioned.

In the machine of FIG. 5, the change in the surface pressure for the cylinders 3 and 4 is effected by an arrangement in which an additional surface pressure is exerted on the backing cloth 1 with the aid ofa respective one of two circulating pressure webs 25 and 26. These pressure webs 2S and 26 are guided over deflecting rollers of which at least one in each case, for instance the deflecting roller 27 and 28 respectively, can be displaced and held in position. in this way the contact pressure force of the corresponding pressure web 25 or 26 can be changed.

A separate speed regulation of the withdrawal rollers 8 and 10 can be omitted in this case.

The pressure webs 25 and 26 are pre-stressed with different forces by way of the deflecting rollers 27 and 28, and 29 and 30 if necessary, acting as tensioning rollers. For this purpose the deflecting rollers 27 and 30 are capable of being displaced and held in position.

In this arrangement the deflecting rollers 27 to 30 acting as tensioning rollers rotate freely so that synchronous circulation of the pressure webs 25 and 26 over the driven backing cloth 1 is ensured.

Endless webs consisting of textile fabric may be used as the pressure webs 2S and 26. However, metal webs with perforations are used for transmitting large tensile forces. These metal webs must be resistant to corrosion and their structure must be made such that the media necessary for the treatment, for instance steam, air and the like, can pass through without hindrance. The total surface pressure is then produced by the sum of the separate forces producing surface pressure, that is to say the tensile force of the backing cloth, the higher speeds of rotation of the two withdrawal rollers 8 and 10 and the tensile forces of the pressure webs 25 and 26.

The methods hereinbefore particularly described lead to optimum decatizing effects. In practice it is found that the best decatizing effects are obtained when the direction of the surface pressure in the steaming phase is on the opposite face of the fabric being treated to that in the suction phase.

With certain qualities of fabric it is advisable to apply a relatively low surface pressure during steaming and a comparatively high surface pressure during suction treatment.

For special kinds of fabric, however, it has been found more advantageous to make the surface pressure during steaming substantially higher than that during suction.

Thus, because the surface pressure in the steaming phase acts in the opposite sense to that in the suction phase, decatizing effects are satisfactorily achieved which could not hitherto be obtained in a continuous operation.

Limit value setting between lower and higher surface pressure, combined so as to produce opposite actions for steaming and suction, give the following results.

If relatively low to intermediate surface pressure during the steaming process is combined with relatively high surface pressure during suction, the result is a soft and voluminous fabric feel, so that the fabric thickness as such hardly changes. Excellent lustre and satisfactory fixing are also obtained.

However, if relatively high surface pressure during the steaming process is combined with relatively low to intermediate surface pressure during suction, the result is a soft but smooth fabric feel with a change in the fabric thickness. A relatively lustreless surface and satisfactory fixation are also obtained.

Since the range between the relatively low and the relatively high surface pressure can be wide, it is consequently possible to achieve considerable differences and nuances over the whole spectrum of the possible decatizing effects.

Good decatizing effects are achieved more particularly when three perforated cylinders are used, if the treatment is carried out on the one hand with different surface pressures and on the other hand with different steam states on the respective cylinders. Thus for example special effects can be obtained if the first cylin der operates with relatively low surface pressure and is supplied with saturated steam, whereas on the following cylinder the operation is carried out with substantially higher surface pressure and with superheated steam. The relatively slight pressing during the saturated steam treatment leads to softening of the feel, whereas the higher surface pressure during the superheating period produces stabilization. When the surface pressure is further increased during the subsequent suction, this causes the required feel and lustre to be produced. However, it also appears to be of interest that a double interaction between steaming on the one hand and suction on the other can be obtained if for instance steaming is carried out with superheated steam and with a relatively high surface pressure on the first treatment cylinder, whereas suction takes place with relatively high surface pressure on the following treatment cylinder, and this is followed by steam treatment with saturated steam under the action of a lower surface pressure on the last cylinder. Firstly, this treatment process permits maximum stabilization, but since the action of the greatly increased temperature leads to hardening of the feel of the fabric and to a decrease in the volume of the fabric, that is to say in the fabric thickness, the subsequent steam treatment with saturated steam under lower surface pressure causes the required feel to be produced and the volume of the fabric to be increased. The apparatus with three treatment cylinders should in each case be followed by an apparatus for cooling the surface of the fabric after the final treatment with steam.

I claim: 1. A method of continuously decatizing a fabric web comprising the steps of applying steam at a steam-applying station to the fabric web as the web traverses a cylindrical path and is subjected to pressure generated by tension applied to a length of backing cloth, and applying suction at a suction-applying station to the fabric web as the web traverses a cylindrical path and is subjected to pressure generated by tension applied to a length of backing cloth, the pressures in the lengths of the backing cloth at the steam-applying station and at the suction 8 applying station being variable independently of one another.

2. A method according to claim 1, wherein the differences in tension in the lengths of backing cloth at the two stations are effected by varying the relative input and output speeds of the backing cloth lengths upstream and downstream of the respective cylindrical paths at the two stations.

3. A method according to claim 1, comprising the further step of applying steam at a further steamapplying station as the web and a length of backing cloth traverse a cylindrical path, the first application of steam employing saturated steam with the web under relatively low pressure and the second application of steam employing superheated steam with the web under relatively high pressure.

4. A method according to claim 1 comprising the further step of applying suction at a further suctionapplying station as the web and a length of backing cloth traverse a cylindrical path, the steam application employing at least saturated steam and both of the suction steps taking place with the web under higher surface pressure than in the steam applying step.

5. A method according to claim 1, wherein the steam-applying station employs superheated steam with the fabric under relatively high pressure, the suction-applying station operates with the fabric under relatively high pressure and a further steam application is effected downstream of the suction-applying station with saturated steam and with the fabric under relatively low pressure. 

1. A METHOD OF CONTINUOUSLY DECATIZING A FABRIC WEB COMPRISING THE STEPS OF APPLYING STREAM AT A STREAM-APPLYING STATION TO THE FABRIC WEB AS THE WEB TRAVESES A CYLINDRICAL PATH AND IS SUBJECTED TO PRESSURE GENERATED BY TENSION APPLIED TO A LENGTH OF BACKING CLOTH, AND APPLYING SUCTION AT A SUCTION-APPLYING TO A LENGTH OF BACKWEB AS THE WEB TRANSVERSE A CYLINDRICAL PATH AND IS SUBJECTED TO PRESSURE GENERATED BY TENSION APPLIED TO A LENGTH OF BACKING CLOTH, THE PRESSURE IN THE LENGTHS OF THE BACKING CLOTH AT THE STREAM-APPLYING STATION AND T THE SUCTION-APPLYING STATION BEING VARIABLE INDEPENDENTLY OF ONE ANOTHER.
 2. A method according to claim 1, wherein the differences in tension in the lengths of backing cloth at the two stations are effected by varying the relative input and output speeds of the backing cloth lengths upstream and downstream of the respective cylindrical paths at the two stations.
 3. A method according to claim 1, comprising the further step of applying steam at a further steam-applying station as the web and a length of backing cloth traverse a cylindrical path, the first application of steam employing saturated steam with the web under relatively low pressure and the second application of steam employing superheated steam with the web under relatively high pressure.
 4. A method according to claim 1 comprising the further step of applying suction at a further suction-applying station as the web and a length of backing cloth traverse a cylindrical path, the steam application employing at least saturated steam and both of the suction steps taking place with the web under higher surface pressure than in the steam applying step.
 5. A method according to claim 1, wherein the steam-applying station employs superheated steam with the fabric under relatively high pressure, the suction-applying station operates with the fabric under relatively high pressure and a further steam application is effected downstream of the suction-applying station with saturated steam and with the fabric under relatively low pressure. 